Synthesis and properties of Au/ZnO nanorods as a plasmonic photocatalyst

• Photocorrosion cracks along the c-axis of ZnO nanorods were observed.
• Au/ZnO show enhanced photocatalytic activity and stability relative to ZnO nanorods.
• SPR effect enhances the light absorption and electrons capture ability of Au/ZnO.
• Au nanoparticles modification induces the formation of surface hydroxyl groups.

It is of great interest to develop plasmonic photocatalysts with high activity and stability recently. In this paper, Au/ZnO nanorods were synthesized via a facile hydrothermal method and used as photocatalysts for methyl orange dye degradation. The results revealed an interesting phenomenon that photocorrosion cracks were produced specially along the c-axis of pure ZnO nanorods for five cycles photodegradation experiments under UV–vis. light irradiation, while Au nanoparticles surface modification can effectively inhibit the occurrence of photocorrosion and improve its photocatalytic activity. The formation of photocorrossion cracks along the c  -axis of pure ZnO nanorods verifies the photogenerated charges may follow the route that electrons migrate to Zn-terminated (0001) plane and holes to O-terminated (0001−) plane. SPR effect of Au nanoparticles enhances the light absorption ability and the electrons capture ability of Au/ZnO nanorods. Moreover, the surface adsorbed hydroxyl groups content is also increased due to Au nanoparticles modification. As Au nanoparticles can capture photogenerated electrons and hydroxyl groups are the favorable holes scavenger, the charges generation and separation in photocatalysis are strengthened. Especially, the charges separation path in Au/ZnO nanorods have changed, thus inhibiting the occurrence of photocorrosion along the c-axis of ZnO nanorods and improving the photocatalytic activity.